Brush holder mechanism



July 17, 1956 c. s, PHlLLlPs 2,755,399

BRUSH HOLDER MECHANISM Filed Jan. 7, 1952 A 36 E 412/1 may j; MESA-yams, mm! 4, 'WEZZZZZ United States Patent BRUSH HOLDER MECHANISM Chester S. Phillips, Florissant, Mo., assignor to The Emerson Electric Manufacturing Company, St. Louis, Mo., a corporation of Missouri Application January 7, 1952, Serial No. 265,239

2 Claims. (Cl. 310244) The present invention relates generally to electrical apparatus, and more particularly to a brush holder mechanism adapted to maintain its brushes in substantially constant pressure contact, and in rigid and secure position relative to an associated commutator, notwithstanding reversal of relative rotation between the brushes and the commutator.

In brief, the present invention contemplates an annular yoke member having pivotally mounted brush holders. A curved brush with an attached pigtail is securely mounted by means of wedging action in each brush holder and a spiral leaf spring is provided for biasing the brush holder and the brush toward the axis of the yoke member. Terminal posts are provided for the attachment of each pigtail and for the electrical connection of the brush holder mechanism with its associated electrical apparatus.

It is an object of the present invention to provide a novel brush holder mechanism that holds its brushes rigidly and securely with no shifting of position upon reversal of rotation.

It is another object of the invention to provide a novel brush holder mechanism which maintains a brush pressure substantially constant for the life of the brushes.

It is another object of the invention to provide a novel brush holder mechanism which maintains a positive contact between the brush and the brush holder.

It is another object of the invention to provide a novel brush holder mechanism in which the brushes are secured in individual brush holders by means of a Wedging action.

It is another object of the present invention to provide a novel brush holder mechanism in which pivotally mounted brush holders are biased to a desired position by means of spiral leaf springs, one end of which is secured in the pivot mounting of the brush holder.

Other objects of the invention are to provide a novel brush holder mechanism which is compact in its design, which has its elements strongly and securely assembled, and which is otherwise well adapted for its intended use.

The foregoing and additional objects and advantages will be apparent from the following description, taken with the accompanying drawings, in which:

Fig. 1 is a plan view of a brush holder mechanism constructed in accordance with the teachings of the present invention, the brush holders being biased to a nonoperative position in the absence of an associated commutator;

Fig. 2 is a view similar to Fig. 1, but with the brush holders maintained in operative position by means of a commutator represented by a dotted circle;

Fig. 3 is a side View, partly in section, of the brush holder mechanism with the brush holders in the position of Fig. 2, the associated commutator being shown in dotted lines;

Fig. 4 is an enlarged fragmentary sectional view taken generally along the line 4-4 of Fig. 3;

2,755,399 Patented July 17, 1956 Fig. 5 is a similarly enlarged sectional view taken generally along the line 5-5 of Fig. 2;

Fig. 6 is a plan view of a removed yoke assembly;

Fig. 7 is a fragmentary sectional view taken generally along the line 77 of Fig. 6;

Fig. 8 is a fragmentary sectional view taken generally along the line 8-8 of Fig. 6;

Fig. 9 is an enlarged plan view of a removed retaining ring;

Fig. 10 is a side view of a brush holder assembly;

Fig. 11 is an enlarged plan view of a removed wedge; and

Fig. 12 is an enlarged plan view of a lock washer.

Referring to the drawings more particularly by means of reference numerals, 15 indicates generally a brush holder mechanism constructed in accordance with the teachings of the present invention. The brush holder mechanism 15 comprises a yoke assembly 16 to which are mounted two brush holder assemblies 17, each of the latter being biased by a spiral leaf spring 18 and securing a brush assembly 19.

The yoke assembly 16 includes an annular yoke member 20 of molded Bakelite, or similar non-conductive material, in which are embedded two studs 21 and two terminal posts 22, as clearly shown in Figs. 6 through 8. It will be noted that each of these embedded elements extends perpendicularly from one face of the yoke member 20 and, further, that the studs 21 and the terminal posts 22 are disposed in respective diametrical opposition. The yoke member 20 is also provided with diametrically opposed mounting holes 23. Each of the studs 21 has a cylindrical flange or head portion 25 extending slightly beyond the face of the yoke member 20 and a cylindrical portion 26 of reduced diameter extending coaxially therebeyond. The extended portion 26 is provided with a longitudinal slot 27 communicating with the free end of the portion 26, and has an annular groove 28 formed adjacent the free end thereof. The terminal post 22 may be of any appropriate shape, such as that clearly shown in the drawings, and has a threaded aperture 30 provided adjacent its free end.

Each brush holder assembly 17 comprises a lever member having spaced parallel extensions 36 containing coaxial holes 37. The remaining portion of the lever member 35 has a somewhat elongated aperture 38 provided with one diagonally disposed face 39, as clearly shown in Fig. 10. It will be noted that the aperture 38 extends in a direction at right angles to the axis of the holes 37. A wedge 40 having a diagonal face 41 complementary with the face 39 of the aperture 38 is disposed within the latter with these complementary faces in flush abutment. The wedge 40 is so dimensioned relative to the aperture 38 as to permit slidable adjustment of the former within the latter, as will appear. The wedge 40 also has a threaded aperture 42 receiving a screw 43, the shank of which extends through an oversized or elongated hole or slot 44 in the Wall of the aperture 38. It will be noted from Fig. 10 that the wedge 40 cooperates with the unfilled portion of the aperture 38 so as to provide a substantially rectangular opening therebetween, which is for a purpose to appear. A lock washer 45 having internal teeth, as clearly shown in Fig. 12, is preferably provided under the head of the screw 43 to maintain the adjusted position of the wedge 40.

The spiral leaf spring 18 has, as best shown in Fig. 4, a flattened inner end slidably received in the slot 27 of the stud 21. The spring 18 has a plurality of convolutions so as to provide a low variation in biasing action over its normal extent of movement, and has its free end shaped, preferably as shown in Fig. 4, to provide biasing abutment with either the lever member 35 or with the wedge 40 associated therewith.

The brush assemblies 19 include an electrical brush 52 having a substantially rectangular cross section and having the general shape of an arc of constant radius with a straight mounting portion extending tangentially therefrom, as clearly shown in Fig. 4. A igtail 53 has one of its ends appropriately embedded and secured in the convex portion of the brush 52 adjacent the adjoining straight portion thereof. The other end of the pigtail 53 is provided with an appropriate electrical terminal'54 for securement to the terminal post 22 by means of a screw 55 received in the threaded aperture 30 of the post 22.

The several elements comprising the brush holder mechanism are assembled as clearly shown in the drawing. It will be noted that the straight portion of the brush 52 is inserted in the rectangular opening provided between the wedge 44) and the aperture 38, after which the screw 43 is tightened to provide firm securement for the brush 52 resulting from a wedging action derived from the cooperation between the face 41 of the wedge 40 and the face 39 of the aperture 38. The lock washer 45, as previously mentioned, maintains the wedge 40 in its adjusted position. The lever member 35 is pivotally received by the stud 21 and is retained thereon by means of a retaining ring 60, as shown in Fig. 9, in serted in the annular groove 28 of the stud 21. As best shown in Figs. 4 and 5, the spiral leaf spring 18 is disposed between the extensions 36 of the lever member 35 with its flattened inner end retained in the slot 27 of the stud 21. One or more shimming washers, such as 61 shown in Fig. 5, may be disposed at either side of the lever member 39 to eliminate end play in the mounting of the latter.

In use, the brush holder mechanism 15 is mounted by means of the mounting holes 23 so as to dispose the yoke member in concentric relation with an associated commutator, the latter shown in dotted lines in Figs. 2 through 4. Thus mounted, it is apparent that the brushes 52 will be in spring biased radial abutment with the associated commutator and will remain so, notwithstanding normal wear of the brushes. Positive contact between the brushes 52 and the terminal post 22 is maintained by means of the direct connection of the pigtails 53 to each of these elements. The secure mounting of the brushes 52 in the lever members 35 and the pivotal mounti and the accompanying drawings have been given by way of illustration and example. It is also to be understood that changes in the form of elements, rearrangement of parts, and substitution of equivalent elements, which will be obvious to those skilled in the art, are contemplated as within the scope of the present invention, which is limited only by the claims which follow.

What is claimed is:

1. An electrical brush assembly comprising an elongated brush holder means at one end for mounting it for pivotal movement onto a motor or the like, the holder projecting outwardly from the pivot axis, the holder having an aperture at its other end to receive a brush and a wedge, the aperture extending laterally across and through the holder transversely to a radius from the pivot axis, the aperture having two opposite walls, one nearest the pivotal axis and one farthest therefrom, and also having two connecting walls, one opposite wall of the aperture sloping toward the axis of rotation; a block-like wedge in the aperture having a surface cooperable with said sloping wall, the wedge having an opposite wall facing the other opposite wall of the aperture; a brush fitted into the aperture engageable by the said opposite wall of the wedge and the facing wall of the aperture; and means to draw the wedge along the sloping wall of the aperture, the sloping surface of the wedge forcing the brush radially with respect to the axis of rotation and clamping the brush in the aperture of the holder, the sloping surfaces being in a direction that provides movement of the wedge along and toward and from the pivot axis of the holder.

2. The assembly of claim 1, wherein the holder has bifurcations at its pivot end, a pivot extending through the bifurcation, a coil spring around the pivot in the space between the bifurcations, connected to the holder to urge it in one direction about its pivot, the aperture being a hole through the holder from side to side thereof, the inner of the opposite walls of which is the sloping wall, the drawing means being a screw, and the brush being shaped to fit into the aperture and being clamped between the said walls.

References Cited in the file of this patent UNITED STATES PATENTS 1,671,533 Lindall May 29, 1928 1,794,291 Hobart Feb. 24, 1931 2,356,105 Uhler Aug. 15, 1944 2,389,941 Stephenson Nov. 27, 1945 2,399,935 Morrill May 7, 1946 FOREIGN PATENTS 131,676 Germany June 17, 1902 659,462 Germany May 4, 1938 762,497 France Jan. 22, 1934 

